Chinese consumers were justifiably angry over the Fonterra fiasco. It not only diminished their confidence in the safety of New Zealand infant formula but resulted in significant collateral damage to the smaller Kiwi exporters that had the foresight and wit (which Fonterra at that stage lacked) to manufacture New Zealand-branded infant formula for the Chinese market.
Key's visit has drawn a line under that episode.
But there is no room for repeat performances, particularly as China is now also building supply lines from Europe and the United States to underpin its increasing demand for dairy products.
Key relates that Xi placed great store on his decision to go to China and offer explanations for the fiasco and the steps that our Government has taken to ensure there is no repeat. "You did the right thing by coming up," Xi told Key. This move had "built trust" into the relationship.
The upshot was Xi's decision to elevate the so-called apology tour into a full-scale official visit complete with a series of deliverables like announcing direct convertibility of the New Zealand dollar with the renminbi.
But Key's biggest takeaway was securing a commitment from Xi to set a new joint goal of $30 billion for bilateral trade by 2020.
This commitment will ensure New Zealand's exports to China will continue to keep pace with development of that economy. Officials point out that last year, New Zealand's exports to China finally topped 20 per cent of total exports, which brings them into line with China's share in the world economy. They say that while there have been negative comments over the risk to New Zealand, there has been a lot less expert discussion of the risks of not being exposed to this large, rapidly growing economy.
Fundamentally, without the continued rapid growth in exports to China, the Government's growth agenda - which is dependent on reaching a target of increasing exports' share of GDP to 40 per cent - is unlikely to be achieved.
This has to be good news at a time when many Western economies are still recovering from the pounding they took in the global financial crisis.
But the Opposition has been determined to try to ensure Key does not get to politically bank the positives from the deepening bilateral relationship.
This is a mistake, especially given Labour's own groundbreaking role in forging bilateral ties with China.
Helen Clark - with her profound understanding of international politics and intuitive approach to cementing deals with political leaders of a vastly different ideological mindset - played the diplomatic pathfinder role.
It was Clark's Government that took the political risk of hurting New Zealand's relationship with that other great power, the United States, by making significant concessions over China's "market economy status" to negotiate the free trade deal. Clark Government ministers Phil Goff and Jim Sutton were at the cutting edge. Their negotiations enjoyed bilateral support from then Opposition trade spokesman Tim Groser.
It is a great pity that this "New Zealand Inc" approach has now been deliberately thrown out the window by Opposition politicians out to make domestic political advantage in election year.
New Zealand exporters were pleased Key was able to make time after his Xi dinner for photo opportunities with their Chinese clients at Wednesday night's Celebration of Dairy dinner.
The event kicked on - as they tend to - elsewhere at the Four Seasons hotel and in various nightspots around Beijing.
Here's the thing: New Zealand exporters are scathing of the Opposition's timing of the Oravida revelations. Beijing expats retain deep suspicions that in the first place, some "low-level" Foreign Affairs official leaked details of Cabinet minister Judith Collins' off-schedule meetings with Stone Shi's Oravida in October, and that the Opposition sat on the issue until the eve of the Prime Minister's China trip to inflict maximum political damage while he was overseas.
The upshot is that, yet again, a positive diplomatic foray by Key has been overshadowed by domestic politics.
These tactics are not new.
Goff and Sutton spewed vitriol over Winston Peters during his first foray as Foreign Minister to an Apec meeting in Korea. And Rebecca Kitteridge's report into the Government Communications Security Bureau was deliberately leaked while Key was in China last year to celebrate 40 years of bilateral diplomatic relations.
It's instructive that Peters - who has been on the end of an own goal - did not personally run the Oravida scandal.
Collins' links with the company of which her husband is a director needs to be examined.
But Labour's decision to rain on Key's parade is not only short-sighted but mean-spirited.
If Labour wins the next election it will be the beneficiary of Key's China-related diplomacy in the same way that the Prime Minister has benefited from Clark's visionary moves.
Reflect on that.
